He sleeps with the fish (6)
I believe the answer is:
kipper
'fish' is the definition.
(type of fish)
'he sleeps' is the wordplay.
I cannot quite see how this works, but
'he' could be 'kipp' and 'kipp' is present in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'with the' acts as a link.
Can you help me to learn more?
(Other definitions for kipper that I've seen before include "One not awake" , "Preserved herring" , "Dried and smoked herring" , "One smoked" , "being in bed?" .)